syzbot


KASAN: slab-use-after-free Read in gfs2_release_folio

Status: moderation: reported on 2025/07/12 10:32
Subsystems: gfs2
[Documentation on labels]
Reported-by: syzbot+bb56b2c14bb9cd927e85@syzkaller.appspotmail.com
First crash: 7d00h, last: 7d00h

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
Read of size 1 at addr ffff888032f1cbe0 by task kswapd0/73

CPU: 0 UID: 0 PID: 73 Comm: kswapd0 Not tainted 6.16.0-rc5-syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:557
 kasan_check_byte include/linux/kasan.h:399 [inline]
 lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5845
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 gfs2_log_lock fs/gfs2/log.h:32 [inline]
 gfs2_release_folio+0x10c/0x570 fs/gfs2/aops.c:669
 shrink_folio_list+0x2113/0x4e90 mm/vmscan.c:1518
 evict_folios+0x4447/0x5500 mm/vmscan.c:4731
 try_to_shrink_lruvec+0x705/0x990 mm/vmscan.c:4892
 shrink_one+0x21b/0x7c0 mm/vmscan.c:4937
 shrink_many mm/vmscan.c:5000 [inline]
 lru_gen_shrink_node mm/vmscan.c:5078 [inline]
 shrink_node+0x314e/0x3760 mm/vmscan.c:6060
 kswapd_shrink_node mm/vmscan.c:6911 [inline]
 balance_pgdat mm/vmscan.c:7094 [inline]
 kswapd+0x147c/0x2830 mm/vmscan.c:7359
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5341:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4359
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 init_sbd fs/gfs2/ops_fstype.c:78 [inline]
 gfs2_fill_super+0x11c/0x20e0 fs/gfs2/ops_fstype.c:1128
 get_tree_bdev_flags+0x40b/0x4d0 fs/super.c:1681
 gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1335
 vfs_get_tree+0x92/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5341:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x18e/0x440 mm/slub.c:4842
 free_sbd fs/gfs2/ops_fstype.c:71 [inline]
 gfs2_fill_super+0x153d/0x20e0 fs/gfs2/ops_fstype.c:1319
 get_tree_bdev_flags+0x40b/0x4d0 fs/super.c:1681
 gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1335
 vfs_get_tree+0x92/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888032f1c000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 3040 bytes inside of
 freed 8192-byte region [ffff888032f1c000, ffff888032f1e000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32f18
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801a442280 0000000000000000 0000000000000001
raw: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 04fff00000000040 ffff88801a442280 0000000000000000 0000000000000001
head: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 04fff00000000003 ffffea0000cbc601 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5316, tgid 5316 (sh), ts 72110942834, free_ts 72110090224
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2619
 new_slab mm/slub.c:2673 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
 __slab_alloc mm/slub.c:3949 [inline]
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
 tomoyo_init_log+0x111f/0x1f70 security/tomoyo/audit.c:264
 tomoyo_supervisor+0x340/0x1480 security/tomoyo/common.c:2198
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x149/0x1e0 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:672 [inline]
 tomoyo_find_next_domain+0x15cf/0x1aa0 security/tomoyo/domain.c:888
 tomoyo_bprm_check_security+0x11c/0x180 security/tomoyo/tomoyo.c:102
 security_bprm_check+0x89/0x270 security/security.c:1302
 search_binary_handler fs/exec.c:1660 [inline]
 exec_binprm fs/exec.c:1702 [inline]
 bprm_execve+0x8ee/0x1450 fs/exec.c:1754
 do_execveat_common+0x510/0x6a0 fs/exec.c:1860
 do_execve fs/exec.c:1934 [inline]
 __do_sys_execve fs/exec.c:2010 [inline]
 __se_sys_execve fs/exec.c:2005 [inline]
 __x64_sys_execve+0x94/0xb0 fs/exec.c:2005
page last free pid 5316 tgid 5316 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
 __slab_free+0x326/0x400 mm/slub.c:4554
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4148 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x224/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 tomoyo_add_entry security/tomoyo/common.c:2132 [inline]
 tomoyo_supervisor+0xbd5/0x1480 security/tomoyo/common.c:2204
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x149/0x1e0 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:672 [inline]
 tomoyo_find_next_domain+0x15cf/0x1aa0 security/tomoyo/domain.c:888
 tomoyo_bprm_check_security+0x11c/0x180 security/tomoyo/tomoyo.c:102
 security_bprm_check+0x89/0x270 security/security.c:1302
 search_binary_handler fs/exec.c:1660 [inline]
 exec_binprm fs/exec.c:1702 [inline]
 bprm_execve+0x8ee/0x1450 fs/exec.c:1754
 do_execveat_common+0x510/0x6a0 fs/exec.c:1860
 do_execve fs/exec.c:1934 [inline]
 __do_sys_execve fs/exec.c:2010 [inline]
 __se_sys_execve fs/exec.c:2005 [inline]
 __x64_sys_execve+0x94/0xb0 fs/exec.c:2005
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888032f1ca80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888032f1cb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888032f1cb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff888032f1cc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888032f1cc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/08 10:22 upstream d7b8f8e20813 4f67c4ae .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_release_folio
* Struck through repros no longer work on HEAD.